1. Field of the Description
The present invention relates, in general, to displays providing a three dimensional (3D) effect without use of special glasses such as, but not limited to, a Pepper's Ghost display, and, more particularly, to displays (or display assemblies) and display methods that utilize a dynamic (on/off, movable in location, and/or variable in size) mask to enhance a displayed (e.g., projected) virtual image such as the image of a character or object selectively positioned within a real life set or set with physical objects and/or characters as in the case of many Pepper's Ghost displays.
2. Relevant Background
There are numerous settings where it is desirable to create a unique visual display. For example, theme or amusement parks may include rides or walk-through attractions where guests (or “viewers”) are entertained by a unique visual effect or illusion. Pepper's Ghost is an illusionary technique used by magicians, by ride or attraction designers, and others to produce a 3D illusion of a latent or ghost-like image. Using a simple piece of plate glass and special lighting techniques, Pepper's Ghost systems can make objects appear and disappear within a scene or room.
Generally, these systems include a main room or scene that is readily viewed by a guest or viewer and a hidden room that is not visible to the viewer. Both rooms are typically identical in their physical structure including furniture and other objects except that the hidden room may include additional objects or characters such as a ghost or other character. A large piece of glass or a half-silvered mirror is situated between the viewer and the scene at an angle, such as at about 45 degrees. When the main room is lit and the hidden room is darkened, the viewer only sees the main room as the hidden room does not reflect from the glass. The sheet of glass is itself hard to see as it typically is quite large so that it extends across the entire view of the main room.
Pepper's Ghost (e.g., the character in the hidden room) then becomes very visible to the viewer when the entire hidden room or portions such as the ghost or other character are brightly lit. Since only a portion of the light cast upon the ghost or other objects in the hidden room is reflected from the glass, the reflected images appear as latent or ghostly images relative to the objects in the main room, e.g., the reflected images or images superimposed in the visible room may appear to float. The Pepper's Ghost image is a 3D image that may be a still image or animation may be provided such as with animatronics providing the “ghost” or by placing a live actor in the hidden room. In many systems, a 2D display is used as these displays are more dynamic and controllable and do not require a live actor or expensive animatronics. However, this results in a 2D image or flat object being positioned within a 3D set, e.g., the main room of the Pepper's Ghost display. In a broad sense, the Pepper's Ghost systems may be thought of as implementing autostereoscopy, which is generally a method of displaying 3D images that can be viewed without the use of headgear or glasses on the part of the user.
FIGS. 1A and 1B illustrate a traditional layout for a Pepper's Ghost display assembly 100 for use in creating a 3D display 150 for a viewer 105. The assembly 100 includes a display scene or real world set 110, a background prop 112, and a foreground prop 114. The props 112, 114 are physical objects such as pieces of furniture that a “ghost” may walk among or, as shown for simplicity's sake, a box 112 and a ball 114. A sheet or piece of glass (e.g., a beam splitter) 118 is positioned at an angle (e.g., 45 degrees) between the scene 110 and the expected or planned position of the viewer 105 (or the viewer's point of view (POV)) or an outer display surface/window. The glass 118 is at least partially transparent such that the background prop 112 and the foreground prop 114 are visible through the glass 118 as light 113 travels through the glass 118 to the viewer or viewer's eyes 105 as shown at 115. A display device 120, such as a typical 2D monitor or a hidden room/scene that can be selectively lit, is provided in the display assembly 100 and is used to display an image 124 such as the two-dimensional pyramid shown in FIG. 1A. The foreground prop 114 is in front of the “ghost” in image plane 126 but behind the beam splitter/glass pane 118.
Light 125 travels toward the beam splitter 118 where it is reflected 128 from the front (or viewer-side) of the beam splitter 118 toward the viewer 105. In this manner, a reflection 127 of the displayed image 124 is visible by the viewer 105 concurrently with light transmitted from the props 112, 114, and the reflection 127 may appear to be located (e.g., as a “ghost” or virtual image) between the background prop 112 and the foreground prop 114 through proper spacing of the display surface 122 relative to the front surface of the glass 118 and the locations of the props 112, 114. An additional foreground prop could be provided in front of the glass 118, and such a prop would occlude the “ghost” on plane 126 and background objects such as prop 112.
In the traditional Pepper's Ghost display assembly 100, a partially reflecting pane of glass or beam splitter 118 is used to overlay reflections 127 of a physical object or images 124 from a video or still monitor or display device 120 on a real world scene 110. As shown in FIG. 1B, the reflected object 154 may be positioned between the background prop 152 and the foreground prop 156 from the perspective of the viewer 105, e.g., the virtual character/object plane 126 is between props 112, 114 in scene 110. Unfortunately, the virtual image (or reflection of the virtual or displayed object 124) 154 is semi-transparent (or translucent) and low contrast. This can be seen in FIG. 1B with the background object 152 being visible at 159 through the virtual image 154. Further, the image 154 appears flat or two-dimensional and is incapable of casting its own shadow as would normally be expected of a solid object in scene 110. The 3D effect is also spoiled in part when the reflection 127 is in front of the foreground image 156 as shown at 158. The translucence, lack of shadows, and flat appearance combine to spoil or hinder for a viewer 105 the illusion of a solid, virtual object integrated into the scene 110.
In some more recent Pepper's Ghost display assemblies, a dynamic mask is provided at the virtual character's location within the set (e.g., within the set 110 of assembly 100 at the virtual character plane) behind the beam splitter. The dynamic mask is used to make the virtual character opaque and high contrast. In these assemblies, the dynamic mask is typically produced using a liquid crystal display (LCD) panel without its back light so that the LCD panel can be controlled to be either opaque (when the virtual character or Pepper's ghost is displayed) or transparent (when the virtual character is not being displayed).
An alternative method of creating the virtual character involves projection onto a scrim placed in the set, and the scrim may be formed from an open weave material such that it is semi-transparent and low contrast against a lit background. In yet another alternative method, a transparent self-emissive display (e.g., a transparent OLED) can also be used to create a virtual character in the set. Since the transparent self-emissive display does not block the background light, it is also semi-transparent and low contrast. In both of these alternative methods, a dynamic mask placed behind the virtual character-generating screen (scrim or transparent OLED) may block the background and provide a black level so as to create an opaque and high contrast character.
A challenge for such advanced Pepper's Ghost or scrim-based display assemblies is that the mask area preferably should be able to cover the entire set to provide proper occlusion and other optical effects regardless of the location of the ghost or virtual character/object. Unfortunately, LCD panels are limited in size unless they are tiled and become increasingly expensive with size. For example, an upper limit of size may be about 100-inches diagonal for commercially available LCD panels, and this limits the advanced Pepper's Ghost display or scrim-based assemblies to small sets that may be unacceptable in many settings such as for use in many theme park rides and larger indoor or outdoor displays. A related challenge is that large room sized LCD-based masks of even modest pixel density would have an extremely large number pixels, which need to be rendered, addressed, and updated. A further challenge is how to produce a well lit and easily viewed display. LCD panels highly attenuate the background scene, e.g., more than 70 percent attenuation, even in areas that are not presently being masked. As a result, the background objects behind the LCD panel must be very brightly lit to be readily viewed by a viewer with the virtual character/object and foreground objects (e.g., foreground objects are lit at a lower level of illumination than background objects to be viewed as having similar illumination as expected if in same room/set).
There remains a need for improved visual display techniques and systems such as for creating or projecting/displaying 3D images. Preferably, such a display system or method would provide a high contrast, solid or opaque-appearing, and 3D dimensional virtual character that can be interspersed or located among/between physical props such as physical foreground and background props. Further, in some cases, it may be useful for the display system and method to be adapted such that displayed virtual objects (or images viewable by an observer) are capable of occluding physical objects (e.g., prevent portion 159 of background prop 152 from being viewed by viewer 105 as shown in FIG. 1B), of being occluded by physical objects in front of them or in front of the virtual character plane (e.g., prevent portion 158 of virtual object 154 from being viewed on or in front of foreground prop 156 as shown in FIG. 1B), and of casting true dynamic shadows. Hence, the new display assemblies and methods may be configured to provide effective dynamic masks in an improved manner.